Journal Article

FZJ-2026-01629

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Terahertz photocurrent probe of quantum geometry and interactions in magic-angle twisted bilayer graphene

Krishna Kumar, R. (Corresponding author) ; Li, G. ; Bertini, R. ; Chaudhary, S. ; Nowakowski, K. ; Park, J. M. ; Castilla, S. ; Zhan, Z. ; Pantaleón, P. A. ; Agarwal, H. ; Batlle-Porro, S. ; Icking, E.RWTH* ; Ceccanti, M. ; Reserbat-Plantey, A. ; Piccinini, G. ; Barrier, J. ; Khestanova, E. ; Taniguchi, T. ; Watanabe, K. ; Stampfer, C.FZJ* ; Refael, G. ; Guinea, F. ; Jarillo-Herrero, P. ; Song, J. C. W. ; Stepanov, P. ; Lewandowski, C. ; Koppens, F. H. L. (Corresponding author)

2025
Nature Publishing Group Basingstoke

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Please use a persistent id in citations: doi:10.1038/s41563-025-02180-3

Abstract: Moiré materials represent strongly interacting electron systems bridging topological and correlated physics. Despite notable advances, decoding wavefunction properties underlying the quantum geometry remains challenging. Here we utilize polarization-resolved photocurrent measurements to probe magic-angle twisted bilayer graphene, leveraging its sensitivity to the Berry connection that encompasses quantum ‘textures’ of electron wavefunctions. Using terahertz light resonant with optical transitions of its flat bands, we observe bulk photocurrents driven by broken symmetries and reveal the interplay between electron interactions and quantum geometry. We observe inversion-breaking gapped states undetectable through quantum transport, sharp changes in the polarization axes caused by interaction-induced band renormalization and recurring photocurrent patterns at integer filling factors of the moiré unit cell that track the evolution of quantum geometry through the cascade of phase transitions. The large and tunable terahertz response intrinsic to flat-band systems offers direct insights into the quantum geometry of interacting electrons and paves the way for innovative terahertz quantum technologies.

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Contributing Institute(s):

1. Halbleiter-Nanoelektronik (PGI-9)

Research Program(s):

1. 5222 - Exploratory Qubits (POF4-522) (POF4-522)
2. GrapheneCore3 - Graphene Flagship Core Project 3 (881603) (881603)
3. 2D4QT - 2D Materials for Quantum Technology (820254) (820254)
4. EXC 2004:  Matter and Light for Quantum Computing (ML4Q) (390534769) (390534769)
5. DFG project G:(GEPRIS)471733165 - Moiré-verstärkte Infrarot-Photodetektion und THz-Emission in verdrehten Graphen-Übergittern (471733165) (471733165)

Appears in the scientific report 2025

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Database coverage:
; BIOSIS Previews ; Biological Abstracts ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; DEAL Nature ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 40 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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